This invention relates to a heat exchanger, particularly an oil cooler, having a stack of disks comprising disk bodies which are stacked on top of one another and are connected with one another by flow-through openings and having a housing enclosing this stack of disks and having a plastic covering, one of the media subjected to the heat exchange respectively flowing through the stack of disks and the housing.
A heat exchanger of this type is known (European Patent Document EP 0 124 217 A1). In the case of this known construction, the disk bodies are first tightly soldered to the two disks forming the later bottom and lid, and subsequently the plastic covering is pushed from the direction of the side of the lid over the still upright edge of the lid with the insertion of a sealing device, into a bottom edge, after which the upright lid edge, also with the insertion of a sealing device, is folded over around the other front side of the covering. This type of manufacturing and mounting of the plastic housing ring on the presoldered basic body results in high expenditures.
It is an object of the invention to develop a heat exchanger of the initially mentioned type in such a manner that the folding-over of the lid and the bottom about the plastic covering and the relatively complicated placing of the plastic covering on the stack of disks will not be necessary. In order to achieve this object, it is provided in the case of a heat exchanger of the initially mentioned type that the bottom and the lid of the housing are also made of plastic, are provided with one fitted sealing device for the sealing on the stack of disks, and are welded to the front sides of the covering, in which case a stop edge is assigned to each sealing device for resting against the stack of disks, and the sealing device is prestressed between the stack of disks and the bottom or lid.
Because of this development, only the stack of disks has to be soldered and is then, as a result of the welding of the lid and of the bottom to the covering, sealed off sufficiently with respect to the lid and the bottom and thus also with respect to the second heat exchange medium. Although it is basically known from the German Patent Document DE 32 47 502 A1 to weld a tube bottom of a heat exchanger made of plastic to a radiator tank made of plastic, the fitting of a sealing device between parts of the plastic bodies, which are to be welded together, does not play a role there. In contrast, the invention suggests a simple construction of a stack of disks which is to be securely sealed off with respect to a housing, in which case this sealing-off previously had taken place exclusively by soldering.
In certain preferred embodiments, it is particularly advantageous for the bottom and the covering to form a one-piece pot-shaped housing onto which only the plastic lid must then still be welded. It is also advantageous according to certain embodiments for the sealing device to be fitted in each case into a recess on the bottom of the housing and in the lid in which case the stop edge may surround this recess. In this case, it is definitely possible to mount the sealing material in a strip shape directly on areas of the recess in such a manner that the desired sealing effect is achieved when the lid is welded to the housing.
However, it is also particularly advantageous in certain embodiments for the sealing device to be mounted as a strip of a sealing material on a thin carrier material, the contour of which is adapted to the recess. The reason is that, in this case, it is sufficient for the sealing device to be placed in the recess surrounded by the stop edge. Advantageously the sealing material may in each case be mounted as closed ring strips on both sides of a carrier foil serving as the carrier material. The stack of disks is inserted and the lid to be mounted which is also provided with a carrier foil with the sealing material is pressed against the housing for so long until in each case the stop edges rest upon one another during the welding operation. In this case, the sealing material may simply be sprayed onto the carrier foil in a strip shape, and these sealing strips may advantageously be applied mirror symmetrically with respect to a plane which extends through the center of the carrier foil and in parallel to its surfaces provided with the sealing material. Since the carrier needs to be only very thin, this results in an easily handled elastic sealing device which can be placed and fitted precisely into the recesses provided for this purpose so that the mounting becomes very simple.
Advantageously, the dimensions of the stop edge and of the recess, on the one hand, and the dimension of the carrier foil and the applied sealing strip, on the other hand, may be coordinated such with respect to one another that the sealing material, after the welding-together of the lid and the housing, is compressed to approximately 60% of its initial thickness and thus is desirably and sufficiently prestressed. In this case, the lid and the bottom may expediently be connected with the covering, or the lid may be connected with the housing, by means of ultrasonic welding, in which case the zones to be welded together, connect with one another while being softened, and the axial force applied in this welding operation is limited by the stop edges which impact on one another. The prestressing which is achieved then, is sufficient on the one hand for achieving a secure sealing with respect to the second heat exchange medium. However, on the other hand, it is also not excessively high to carry the risk of a premature fatigue of the sealing material. Silicone has proven to be useful as the sealing material and, in a simple manner, can be sprayed onto the carrier foil.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.